There is a substantial need for methods of remote sealing and coating. Research has shown that the energy savings potential of sealing duct leaks is on the order of 20% of the furnace or air conditioner energy use (Modera, M. P. (1993 Energy and Buildings, 20:65-75). During the past five years, research has quantified the impacts of residential duct system leakage on HVAC energy consumption and peak electricity demand. A typical California house with ducts located in the attic or crawlspace wastes approximately 20% of heating and cooling energy through leaks and draws approximately 0.5 kW more electricity during peak cooling periods. Besides, given that 25% to 75% of the leaks are not accessible, conventional technologies such as using duct tape or mastic are often not satisfactory. Existing remote sealing technologies have been examined (e.g. introducing a rolling mechanical cart, or unfolding a cylinder in the duct network). Although the application of these techniques might be of interest for some pipe networks (the cart was patented and used for gas pipes and the unfolding cylinder is used to seal large underground pipes), the complexity of a residential duct system does not allow straightforward application of these technologies.
Encapsulants for duct systems have been previously disclosed and some of those have been applied by introducing a fog into the duct system.
Shinno teaches sealing and coating a pipe through the application of a mist to the interior surface of the pipe [U.S. Pat. No. 4,327,132 Method for Lining of Inner Surface of a Pipe (Apr. 27, 1982)]. This patent discusses the use of a multiple component epoxy based mist which is applied with a rapid air stream and then dried in place with the same rapid air stream. It also discusses the withdrawal and revival of residual paint exhausted from the pipe outlet. The Shinno patent calls for multiple gas flows, one to atomize the liquid to be applied and another to blow the mist down the pipe. Shinno also calls for mixture velocities of between 30 meters/second and 100 meters/second.
Koga teaches a method and apparatus for generating a plastic mist for deposition upon the interior surface of a pipe [U.S. Pat. No. 4,454,173 Method for Lining Pipes in a Pipeline (Jun. 12, 1984) and U.S. Pat. No. 4,454,174 Method for Lining Pipes of a Pipeline (Jun. 12, 1984)]. These patents confine themselves to the delivery of a plastic mist to the interior pipe surface. The Koga patents describe the use of a compressor and a vacuum generator to carry the mist through the pipeline. Additionally, these patents teach the use of low air pressure at one stage and high air pressure at another. In the Koga patent a heater is used to maintain the plastic in a liquid form.
Hyodo et al. teaches a method for sealing pipes which comprises feeding an aerosol type sealant into a pipe in the form of a foam [U.S. Pat. No. 4,768,561 Process for Sealing Pipes (Sep. 6, 1988)]. The sealant disclosed is one containing an aqueous resin selected from the group consisting of emulsions and latexes as a main component and being added with a propellant such as Freon 12/Freon 114.